US5147473A
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Permanent magnet alloy having improved resistance to oxidation and process for production thereof
Assignee: Dowa Holdings Co Ltd
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Filing: 1990-08-09
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Granted: 1992-09-15
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Expires: 2010-08-09
Abstract
Abstract A permanent magnet made of an R-Fe-B-C or R-Fe-Co-B-C based alloy (where R is at least one rare-earth element) consisting of its individual magnetic crystal grains that are covered with an oxidation-resistant protective film is promising as a practicable next-generation magnet because of its having not only excellent magnetic properties inclusive of magnetic force that surpasses Sm-Co based magnets but also such highly improved oxidation resistance that may withstand use in practical applications for a prolonged time period without being coated on its outermost exposed surface with an oxidation-resistant protective film. Said protective film surrounding the individual magnetic crystal grains contains at least one, preferably substantially all, of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt. %, preferably 0.1-16 wt. % of said protective film being composed of C.
Inventors
- 👤 Toshio Ueda
- 👤 Yuichi Sato
- 👤 Masayasu Senda
- 👤 Seiji Isoyama
- 👤 Seiichi Hisano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:01
CPC Classifications
C; C22; C22C; C22C1/00; C22C1/04; C22C1/0433; C22C1/0441; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/057; H01F1/0571; H01F1/0572; H01F1/0575; H01F1/0577; H01F1/058
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
103 words
A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 2
Dependent Claim
103 words
A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 3
Dependent Claim
20 words
The permanent magnet alloy according to claim 1 wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 4
Dependent Claim
24 words
The permanent magnet alloy according to claim 2, wherein the rare-earth element is Nd; said oxidation-resistant protective film has a thickness of 0.001-15 μm.
Claim 5
Dependent Claim
36 words
The permanent magnet alloy according to claim 3, wherein said oxidation-resistant protective film has a thickness of 0.005 to 12 μm and C in the alloy composition is in an amount of 0.5 to at 20%.
Claim 6
Dependent Claim
62 words
The permanent magnet alloy according to claim 1, wherein B is an amount of less than 1.8 at. % and greater than 0 at. %; 0.1 to 16 wt. % of the oxidation-resistant protective film comprises C; and the composition of said magnetic alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprises 0.5-20 at. % C.
Claim 7
Dependent Claim
32 words
The permanent magnet alloy according to claim 5, wherein 0.2 to 12 wt. % of the oxidation-resistant protective film comprises C and said oxidation-resistant protective film has a thickness of 0.005-12 μm.
Claim 8
Dependent Claim
19 words
The permanent magnet alloy according to claim 1, wherein said oxidation-resistant protective film has a thickness of 0.001-30 μm.
Claim 9
Dependent Claim
20 words
The permanent magnet alloy according to claim 7, wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 10
Dependent Claim
118 words
A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film which comprises all of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 11
Dependent Claim
118 words
A permanent magnet alloy which is based on a R-Fe-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film which comprises all of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt % of said protective film comprising C, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 12
Dependent Claim
20 words
The permanent magnet alloy according to claim 9 wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 13
Dependent Claim
42 words
The permanent magnet alloy according to claim 10, wherein the rare-earth element is Nd; said oxidation-resistant protective film has a thickness of 0.005 to 12 μm and C in the alloy composition is in an amount of 0.5 to 20 at. %.
Claim 14
Dependent Claim
19 words
The permanent magnet alloy according to claim 9, wherein said oxidation-resistant protective film has a thickness of 0.001-30 μm.
Claim 15
Dependent Claim
20 words
The permanent magnet alloy according to claim 12, wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 16
Dependent Claim
131 words
A permanent magnet alloy which is based on a R-Fe-Co-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 17
Dependent Claim
131 words
A permanent magnet alloy which is based on a R-Fe-Co-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 18
Dependent Claim
20 words
The permanent magnet alloy according to claim 14 wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 19
Dependent Claim
64 words
The permanent magnet alloy according to claim 14, wherein B is in an amount of less than 1.8 at. % and greater than 0 at. %; and 0.1 to 16 wt. % of the oxidation-resistant protective film comprises C; and the composition of said magnetic alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprises 0.5-20 at. % C.
Claim 20
Dependent Claim
32 words
The permanent magnet alloy according to claim 16, wherein 0.2 to 12 wt. % of the oxidation-resistant protective film comprises C and said oxidation-resistant protective film has a thickness of 0.005-12 μm.
Claim 21
Dependent Claim
19 words
The permanent magnet alloy according to claim 14, wherein said oxidation-resistant protective film has a thickness of 0.001-30 μm.
Claim 22
Dependent Claim
20 words
The permanent magnet alloy according to claim 18, wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 23
Dependent Claim
29 words
The permanent magnet alloy according to claim 14, wherein the rare-earth element is selected from the group consisting of Y, La, Ce, Nd, Pr, Tb, Dy, Er and Sm.
Claim 24
Dependent Claim
146 words
A permanent magnet alloy which is based on a R-Fe-Co-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film which comprises all of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20%, C up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 25
Dependent Claim
146 words
A permanent magnet alloy which is based on a R-Fe-Co-B-C system, R being at least one of the rare-earth elements including Y, comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film which comprises all of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20%, C up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 26
Dependent Claim
20 words
The permanent magnet alloy according to claim 21 wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 27
Dependent Claim
23 words
A permanent magnet alloy according to claim 21 or 22 wherein 0.1-16 wt % of said oxidation-resistant protective film consists essentially of C.
Claim 28
Dependent Claim
30 words
The permanent magnet alloy according to claim 21, wherein the rare-earth element is selected from the group consisting of Y, La, Ce, Nd, Pr, Tb, Dy, Ho, Er and Sm.
Claim 29
Dependent Claim
19 words
The permanent magnet alloy according to claim 21, wherein said oxidation-resistant protective film has a thickness of 0.001-30 μm.
Claim 30
Dependent Claim
20 words
The permanent magnet alloy according to claim 25, wherein said magnetic crystal grains have a particle size of 0.5-50 μm.
Claim 31
Dependent Claim
19 words
The permanent magnet alloy according to claim 25, wherein 0.1-16 wt. % of said oxidation-resistant protective film comprises C.
Claim 32
Dependent Claim
107 words
In an improved permanent magnet made of a R-Fe-B-C system alloy, R being at least one of the rare-earth elements including Y, the improvement comprising said alloy comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 33
Dependent Claim
107 words
In an improved permanent magnet made of a R-Fe-B-C system alloy, R being at least one of the rare-earth elements including Y, the improvement comprising said alloy comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 34
Dependent Claim
13 words
The permanent magnet according to claim 28, wherein the rare-earth element is Nd.
Claim 35
Dependent Claim
136 words
In an improved permanent magnet made of a R-Fe-Co-B-C system alloy, R being at least one of the rare-earth elements including Y, the improvement comprising said alloy comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 36
Dependent Claim
136 words
In an improved permanent magnet made of a R-Fe-Co-B-C system alloy, R being at least one of the rare-earth elements including Y, the improvement comprising said alloy comprising individual magnetic crystal grains having a particle size of 0.3-150 μm and which are covered with an oxidation-resistant protective film, with 0.05-16 wt % of said protective film comprising C, and up to 30 wt %, not inclusive of zero wt %, of said protective film comprising Co, and the composition of said magnet alloy as the sum of the magnetic crystal grains and the oxidation-resistant protective film comprising 10-30% R, less than 2%, not inclusive of zero percent, of B, 0.1-20% C, up to 40%, not inclusive of zero percent, of Co, all percentages being on an atomic basis, with the balance being Fe and incidental impurities.
Claim 37
Dependent Claim
29 words
The permanent magnet according to claim 30, wherein the rare-earth element is selected from the group consisting of Y, La, Ce, Nd, Pr, Tb, Dy, Ho, Er and Sm.
Claim 38
Dependent Claim
45 words
The permanent magnet according to claim 30, wherein said magnetic crystal grains have a particle size of 0.5-50 μm, C in the film is in an amount of 0.2-12 wt. %, and C in the alloy composition is in an amount of 0.5-20 at. %.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-09-15 | 1996-03-16 | 1996-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-15 | 2000-03-16 | 2000-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-15 | 2004-03-16 | 2004-09-15 | $7700.00 | Window Closed / Lapsed |